N-Butanol and ethyl acetate are commercially significant organic compounds having use in a wide variety of applications and which are produced in quantities exceeding 1 million tons per year. N-Butanol can be produced from several different reactions. The most common method for making n-butanol is hydroformylation. Propylene reacts with syngas over cobalt or rhodium catalysts at high pressures to produce an aldehyde (butyraldehyde), which is then hydrogenated over a nickel catalyst to give the alcohol. The drawbacks of such a process include the high energy costs associated with the generation of syngas, the use of a potentially non-renewable feedstocks (propylene and syngas are typically sourced from petroleum and natural gas, respectively), and the complexity of the process which requires multiple reactors and, typically, homogenous hydroformylation catalysts.
N-Butanol can also be produced from an aldol condensation reaction followed by hydrogenation. This method converts acetaldehyde to butanols, although the high toxicity and limited availability of acetaldehyde make such a process unattractive. Some processes, for example U.S. Pat. Nos. 1,992,480 and 8,071,823 both of which are incorporated herein by reference in their entirety, utilize a gas phase reaction to provide butanol.
Direct fermentation of sugars is another process for production of n-butanol. As a bioprocess this method suffers from long process times and large separation requirements in addition to the need for specialized microbes necessary to make butanol directly from sugars.
Ethyl acetate can also be produced from several different reactions. The most common method for making ethyl acetate is the esterification of acetic acid and ethanol. This reaction requires two raw material supplies with the associated storage or production facilities. In locations without a sufficient supply of reliable, inexpensive acetic acid, this process may not be economically viable.
Ethyl acetate can also be produced from the oxidation of ethanol over supported precious metal catalysts. The high costs of precious metal catalyst can also make this option uneconomical.
The Tishchenko reaction (dimerization of aldehydes into esters) is another alternative process for production of ethyl acetate. Dimerization of acetaldehyde results in ethyl acetate, however, aldol condensation also occurs, resulting in by-products such as 2-butanone and 2-propanol, both of which form azeotropes with ethyl acetate. In addition, the Tishchenko reaction requires a supply of acetaldehyde, which may not be readily available and can be difficult to store and handle due to its high toxicity.
1-Hexanol and 1-octanol are both made industrially via oligomerization of ethylene using triethylaluminum, followed by oxidation of the alkylaluminum intermediate. In this process, the triethylaluminum does not serve as a catalyst, but rather is a reactant that is not easily regenerated. In particular, the reaction scheme starts with metallic aluminum and results in the formation of aluminum oxide and/or hydroxide upon completion of the reaction. The triethylaluminum is expensive since it requires metallic aluminum as a precursor. The triethylaluminum is also a pyrophoric material and presents hazards for using and storing. This process also requires a potentially non-renewable feedstock (ethylene) typically source from steam cracking of petroleum.